The TomTom Touch is not just an activity tracker, it's a fitness tracker. Touch measures your percentage of body fat and muscle, also known as your body composition, on top of other 24/7 activities like steps, distance, sleep, heart rate and calories burned. Why body composition? Body composition is a great indicator of your fitness level and overall health. Knowing how your body fat and muscle percentages change over time gives you insight into your progress and shows the results of all your efforts: diet, exercise, and active lifestyle.